It seems somehow fitting that at the end of 2009—and at the end of this bizarre decade—a couple of the online experiments hailed by many as ground-breaking trends are turning out to be simply large-scale fads. First I heard rumblings about editors leaving Wikipedia in droves. Now there are signs that teenagers are devising ways to end their addiction to Facebook.

Wikipedia started in 2001 with the intention of creating free access to “the sum of all human knowledge.” The underlying intention was naively democratic. In theory anyone could participate, starting a new topic or editing an existing page. Wikipedia’s editorial pool actually peaked in March of 2007 at 820,000 (it is worth noting that contributors are above average in technical knowledge and that only 13% of them have been women).

The so-called wiki democracy proved to be an unruly herd. There were hoaxes, misinformation, and a great deal of bickering on discussion pages. By then there were plenty of rules, several committees, and a growing hierarchy of editors with special privileges. “Wikipedia is becoming a hostile environment,” says Felipe Ortega, who has analyzed Wikipedia data regarding its editorial process. “Many people are getting burned out when they have to debate about the contents of certain articles again and again.” And the online encyclopedia now is constantly threatened by vandals who insert irrelevant political views, obscure jokes, or self-serving marketing messages into articles left and right.

Of course the other obvious reason for the decreasing participation is that, with three million articles in the English version, there are fewer and fewer things to write about. The days when anyone could freely start a new page are over. New pages are reviewed before they are posted. Most are deleted as irrelevant. Newcomers who try to edit a page are often told they have broken a rule. (I have written about this transformation elsewhere.) Wikipedia is trying to create diversity in its contributors. It is launching a new editing system to replace the Byzantine one that newbies have always had to struggle with. But it remains to be seen if Wikipedia just got too big to prevail.

Crowdsourcing, as the wiki method of building content is called, is based on the assumption that mass collaboration will inevitably separate the wheat from the chaff and create the “wisdom of crowds.” Books such as Don Tapscott “Wikinomics: How Mass Collaboration Changes Everything” and James Surowiecki’s “The Wisdom of Crowds” have expressed this decade’s enthrallment with all things wiki. What seemed to be a trend, however, a few years ago, shows signs of a fading fad now.

Facebook could be heading for a crisis as well, but for entirely different reasons. People, especially teenagers, are discovering that they have real lives (RL, as opposed to VL—virtual life) that demand some attention from time to time, such as when they are trying to complete college applications or studying for finals. Instead of constantly updating their own records of their lives and reading messages from friends, some young adults are choosing to conduct their social lives offline.

For many, Facebook has actually become an addiction. Young adults are consequently devising strategies for weaning themselves “off” the social networking website. Some make pacts with friends. Other have someone manage their password so they can only view their Facebook page on weekends or once a month. The live feed format recently added to Facebook has made it especially difficult to turn away from the site. Educator Rachel Simmons explains it this way: “You’re getting a feed of everything everyone is doing. You’re literally watching the social landscape on the screen, and if you’re obsessed with your position in that landscape, it’s very hard to look away.”

It’s unclear how widespread the deactivation and limited access strategies have become. Facebook won’t say how many users have deactivated their accounts. It could be that yet another Internet phenomenon is in for some fundamental changes. Other institutions, however, are surely here to stay. Take heart, Internet aficionados, we’ll always have Google.